1. Field of the Invention
The present invention relates generally to an image processing system and method, and an image display system.
2. Description of Related Art
As conventional image display devices, there are two-types of impulse type display devices (e.g., CRTs, field emission type display devices (which will be hereinafter referred to FEDs)), which continue to emit light only for the afterglow time of a fluorescent substance after writing an image, and hold type display devices (e.g., liquid crystal displays (which will be hereinafter referred to as LCDs), electroluminescent displays (which will be hereinafter referred to as ELDs)), which continue to hold the display of the last frame until a new image is written. There are also plasma display panels (which will be hereinafter referred to as PDPs) and projectors using a film. The PDP is a system for carrying out a gradation display in time axis directions, which is called a pulse width modulation method, so that the PDP is considered as a kind of hold type. The projector using a film is considered as a hybrid type for carrying out irradiation and non-irradiation of an image for a frame period. As other systems of a hybrid type, a system using a LCD and a shutter has been proposed by Japan Association of Broadcasters (see Japanese Patent Laid-Open Publication No. 1997-325715), and a system using a LCD and a flashing back light has been proposed by International Business Machines Corporation (see Japanese Patent Laid-Open Publication No. 1999-109921).
The hold type display device has a problem in that the blurred phenomenon and the discontinuous display phenomenon are caused during the display of a moving picture. As shown in FIG. 16, the blurred phenomenon is caused by the fact that if observer's eyes track the movement of a moving object, the eyes observe the picture while moving on the last frame picture, although the same picture of the last frame continues to be displayed in a frame before the picture of the next frame is displayed. That is, the tracking motion of eyes has continuity, so that fine sampling is carried out. As a result, blurring is observed by carrying out visual recognition so that a picture between the first frame and the second frame is buried. On the other hand, the discontinuous display phenomenon is particularly observed in the case of a fixation viewpoint, and is based on the fact that pictures of several frames are substantially simultaneously observed as shown in FIG. 17. These phenomena depend on the speed of the moving object. If the speed of the moving object increases, the correlation between the last frame picture and the next frame picture deteriorates, so that the phenomena are more conspicuously observed.
On the other hand, the impulse type display device has a problem in that the picture jumping phenomenon is caused during the display of a moving picture. Although this picture jumping phenomenon is observed similar to the above described discontinuous display phenomenon, it is described by a different expression since the cause of occurrence is different from that of the discontinuous display phenomenon. The picture jumping phenomenon is also particularly caused at a fixation viewpoint. In the impulse type display device, since display disappears between frames, in other words, a picture having no correlation right before a next frame is not displayed, so that blurring decreases. On the contrary, the picture jumping phenomenon is more conspicuously visually recognized even in usual observation circumstances. The picture jumping phenomenon depends on the speed of a moving object and a frame frequency (the reciprocal of a frame period). It is considered that the reason why the picture jumping phenomenon is caused is as follows. If the speed of the moving object increases with respect to the frame frequency, although a correct image is projected on retinas in time series, the image between the last frame and the next frame disappears as shown in FIG. 18, so that the interpolation processing is not sufficiently carried out in brains.
Thus, in conventional image display devices, there is a problem in that the picture quality deteriorates in accordance with the displayed contents. It seems that the deterioration of the picture quality is more conspicuous with the increase of images having clear contours, i.e., images including high spatial frequency spectra, such as images obtained by computer graphics or the like and images picked up by a high-speed shutter video camera.